A phosphorus accumulation organism strain AP3 with Fe (Ⅲ) as electronic acceptor was screened from activated sludge through such processes as dilution plate method, poly P, PHB staining and ferric citrate reduction. Its 16S rDNA is identical to that of Pseudomonas mosseliisp ATCCBAA 99 at 99% level. By comparing the AP3 being cultured in ferric citrate fluid medium and the one in non ferric fluid medium at 27 ℃, it was found that ferric citrate fluid medium was beneficial for the AP3. AP3 cultured in non ferric fluid medium showed significant anaerobic and phosphorus releasing characteristic, the phosphorus releasing amount of which was 3.68 mg·L-1. AP3 cultured in ferric fluid medium was also characterized by anaerobic and phosphorus releasing property at the first stage, the phosphorus releasing amount of which was 662 mg·L-1，which was higher than the former; And at the second stage which started from the 10h, it was characterized by anaerobic and phosphorus accumulating property, the phosphorus accumulating amount of which was 5.89 mg·L-1. Fe (Ⅲ) is the electron acceptor of AP3 which shows typical anaerobic and phosphorus absorbing property.